1. Field of the Invention
This invention relates to a control system for controlling an internal combustion engine which is provided with at least one fuel injection pump, more particularly to such control system which comprises for the control of the fuel injection pump a control rod, a servomotor, which is adapted to be mechanically coupled to said control rod, and a microcomputer for controlling said servomotor in dependence on operating conditions of the engine and on the position of an arbitrarily operable travel control lever.
2. Description of the Prior Art
A known control system of that kind is disclosed in No. EP-A-0 044 289.
The operating conditions of the engine may be indicated, e.g., by the charging pressure, the engine temperature, the ambient temperature, the fuel temperature, the engine speed or other parameters. One of the signals delivered to the microcomputer is generated by a sensor in response to the instantaneous position of the arbitrarily operable travel control lever. The control rod for controlling the quantity of fuel delivered by the fuel injection pump is operated in response to the output signals of the microcomputer so that a separate stop for limiting the quantity of fuel delivered by fuel injection pump is no longer required.
That known control system is relatively simple and comprises only a few movable parts, but has the important disadvantage that in case of a failure of the electric system comprising the sensors, the microcomputer and the servomotor the internal combustion engine can no longer be controlled because an arbitrary control action is no longer possible. For this reason the system is unreliable and this is not tolerable, e.g., in connection with ship engines.